The present invention relates to a device and a method for setting up a connection in a telecom system.
Telecom systems composed of several different types of telecom networks have been developed. The networks can be circuit switched as well as packet switched and can have different types of signal format. The networks, also those packet switched, may transfer information in real time and in some cases provide services of high quality, e.g. high availability, good audibility and uninterrupted communication. The networks are however expensive for the operators to manage if the demand for the high quality shall be maintained. These costs can be decreased if the present networks are replaced by an entirely new, packet switched network. This would, however, imply capital destruction. Efforts have therefore been made to create a gateway, through which certain networks can be connected together while maintaining a good quality of the services.
The British patent application GB 2 323 246 A describes a gateway through which mostly internet telephones can be interconnected. These telephones all use signal formats for internet telephony, but these signal formats often differ somewhat from each other. The gateway sets up the connection by converting a message in one signal format for an incoming connection to an intermediate format and thereupon converting it to a format for an outgoing connection. When the message is in the intermediate format it can be signal treated in different respects, e.g. by adding a function for tone detection or speech recognition to the connection.
The international patent application WO 99/05830 describes a telecom system in which a mobile telephone network for speech and text transmission is interconnected with an internet. In an interconnecting unit transferred signals between the signal protocols of the mobile telecom networks and the signal protocols for internet telephony are converted. At the conversion an intermediate PCM-coded signal format can be used. Some examples are given for interconnection of mobile telecom networks and standard IP-networks or IP-routers. Also examples of interconnection of IP-networks with mobile telecom networks having TDMA-protocols for speech or text transmission are indicated.
Also the European patent application EP 0 841 831 A2 describes a telecom network with a gateway which transforms signal formats between different sub-networks. Solutions thus known for interconnecting different telecom networks suffer from drawbacks. One of these is that only some stated types of networks can be interconnected if one solution is chosen, whereas a limited set of other networks can be interconnected if another solution is chosen. Another drawback is that known solutions are little flexible so as to make it complicated to introduce new telecom functions for signal treatment of the connections. It is also complicated to increase the number of different types of networks with different signal formats which can be interconnected.
The present invention tackles the problems associated with the above mentioned drawbacks, when a connection is set up in a telecom system composed of different telecom networks. Thus, the main problem to be able to set up a connection via all kinds of existing telecom networks is tackled, independently of their respective signal formats, and to be able to add all different existing telecom functions to the telecom connection.
A further problem tackled is to be able to connect to new networks or networks thus far unknown to an operator, the specifications of which are new or are thus far unknown to the operator. New or earlier unused telecom functions shall be able to be included in the management of the telecom connections. These changes shall be able to be executed without affecting earlier implementation of telecom functions or connections to different telecom networks.
Another problem to be tackled is that the different telecom functions and the functions for connecting to the networks shall be able to be hardware or software located anywhere in a gateway interconnecting the networks.
Furthermore the problem to be able to supplement a set up connection with a telecom function and to set up still another subscriber in the connection, is tackled.
In the present description it is stated how to set up a connection in a telecom system. The connection arrives on a certain incoming signal format and is converted to a common signal format, and thereafter necessary telecom functions are added to the connection. The latter is connected further after having been converted from the common signal format to an outgoing signal format. The above mentioned problems with this connection are solved by a method and a device wherein a first control unit receives control signals for the connection from a server. A second control unit associated with the telecom functions exchanges signals with the first control unit and looks for one of the telecom functions that shall be added to the connection. A third control unit associated with the switch functions of the gateway receives signals from the first control unit and aided by these signals is able to set up the telecom function and required switch function in the connection.
Somewhat more exactly the problems are solved by providing for the first control unit information regarding the signal format and network address of the incoming connection. The second control unit receives the signals from the first control unit and aided thereby finds a free telecom function, the address of which is returned to the first control unit. The latter one requires from the third control unit to set up the switch function corresponding to the network address of the connection and also set up the addressed telecom function in the connection. The third control unit performs the required set up so that the connection is received in the gateway and is converted to the common signal format.
The connection is further set up by the first control unit receiving from the server a node address for the connection. The third control unit looks for a free subconnection to the node address and establishes the subconnection and indicates this to the first control unit. This control unit instructs, in the same way as earlier, a signal format converter and a switch function required for reconverting from the common signal format to a signal format for the established subconnection.
There is thus an aim of the present invention to be able to set up a connection in a telecom system that includes all kinds of existing telecom networks, independently of the signal format, and to add different telecom functions to the connection.
Another aim is to be able to connect to new telecom networks and incorporate new telecom functions for setting up a connection. This shall not affect the gateway otherwise, in other words, it shall not affect the way of connecting to earlier networks or the implementation of earlier telecommunication functions.
Still a further aim is that the telecom functions and the switch functions for connecting the networks shall be able to be hardware or software which is located anywhere within a gateway.
There is an advantage with the invention that the gateway easily can be set up for interconnecting all known types of telecom networks.
Another advantage is that older telecom networks can be used, which results in low costs.
A further advantage is that new telecom functions and telecom networks easily can be used.
The invention will now be described more closely by means of preferred embodiments and with reference to the attached drawings.